In order to achieve a compact, lightweight, stable fiber-coupled Terahertz Time-Domain Spectrometers(THz-TDS), Theoretical and experimental studies on THz-TDS excited by a 1 550 nm fiber femtosecond lasers are carried out in terms of dispersion compensation, nonlinear effects, polarization effects and antenna parameters. As a result, a flexible THz spectroscopy system with a spectral bandwidth over 4.5 THz and a dynamic range of 70 dB is realized. In addition, the system is 12.3 kg in weight and the optical module is 250 mm×90 mm×50 mm in size. The system is tested in terms of stability at different conditions of mechanical vibrations and environmental temperatures. The results show that the system is highly robust and could be applied for industrial applications.